Filter device with closing arrangement and key opening connection

ABSTRACT

A filter device has a housing with connections for a fluid and can be secured to a filter pot. The filter has a filter element secured by a holder. A closure prevents the undesired leakage of fluid. The closure has two sealing plates with at least partly bound openings in mutually staggered array in two different planes. The openings can be mutually moved under the effect of a power store for closing or opening the openings. As the filter pot is moved further away from the housing, the closure gradually seals at least one of the connections and/or the filter pot off from the environment. The filter device has a universally usable closure which can be economically produced, requires little space inside the device and operates reliable.

FIELD OF THE INVENTION

The present invention relates to a filter device with a housing havingconnections for fluid flow. The housing can be connected with a filterpot having at least one filter element held tightly by an elementholder. A closing arrangement prevents any undesired fluid leakage uponremoval of the filter pot from the housing.

BACKGROUND OF THE INVENTION

In filter devices, contaminated fluid can be guided through a feed lineinto a filter pot incorporating the filter element, flowing from theoutside inward through the filter element. In this manner, the pollutingmaterial particles are separated from the fluid. Cleaned in this manner,the fluid proceeds from the inside chamber of the filter element andthrough the associated drain from the filter housing to the use point inthe hydraulic or other fluid circuit which is being supplied with cleanfluid.

After an extended period of time in use, such filter element becomescontaminated, and must be replaced with a new, clean filter element. Forthis purpose, the filter pot with the filter element arranged therein isscrewed or threaded out of the housing and then removed according toconventional practice. During this unscrewing step, the element holderis usually moved radially along with the filter element. The packing orsealing ring provided between element holder and housing can be damagedin the process. Especially in the reverse situation, following exchangeof the filter element and replacement of the filter pot in the housingby screwing in and out, crushing, drilling and sliding movements mayoccur in the packing ring. Such movements tend to negatively influencethe sealing effect of the packing ring, so that unfiltered fluid canbecome mixed with already filtered fluid.

During the exchange process the filter pot is filled with fluid, such ashydraulic oil, liquids which are flame-resistant, biologicallydecomposable liquids or polluted water. Frequently fluid leaks outinadvertently into the environment and leads to pollution of theenvironment. Such pollution occurs most often when the exchanging filterelements in working machinery located outside.

The filter devices disclosed in German Patent No. 30 31 431 C2 andGerman unexamined publication 26 23 409 have closing arrangementsconstructed as reflux check valves of elastomeric material. A valve inthe form of a one-part flange member surrounds the element holder forthe filter element. As soon as fluid is fed in through one of theconnections, in the form of a feed line, the elastically flexibleflange-like valve opens. Otherwise, the valve is held in its closedposition because of its elasticity, and prevents undesired fluiddischarge into the atmosphere through the connection or when the filterpot is removed out of this assembly. No closing of the fluid-carryingconnections in the housing of the device is provided. The known closingdevices require considerable structure space in the area of the elementholder and do not always function reliably during operation. Especiallywith the pressure peaks in the connections or even in the case of anundesired reversal of the fluid flow direction, an inversion or tearingapart of the plate- or disk-like elastomeric sealing border of theflange part can cause the closing arrangement to become unserviceable.This last occurrence leads to breakdown of the filter device.

SUMMARY OF THE INVENTION

Objects of the present invention are to provide a filter device having auniversally adjustable closing arrangement which can be produced atreasonable cost, requires only limited construction area and functionsreliably during operation.

The foregoing objects are basically obtained by a filter devicecomprising a housing having first and second fluid connections, a filterpot and closing means in the housing to prevent undesired fluid leakage.The filter pot has an open end reasonably coupled to the housing, has afilter element with an inside chamber and has a filter holder secured tothe filter element. The closing means has relatively movable first andsecond closing plates partially defining and limiting first and secondopenings in the closing plates, respectively. The first and secondopenings are relatively offset in two different planes. Separate powermeans relatively moves the closing plates to close continuously andprogressively the openings to seal one of the first fluid connection,the second fluid connection and the open end of the filter pot uponincreasing separation of the filter pot from the housing.

The closing arrangement requires only a small structural space withinthe device. The path of movement of the essentially flat closing platesfrom the open position into closed position, and vice versa, is thuslimited and reliable. Disturbance-free operation is attained because ofthe linear, uniform movement of the closing plates. With this closingarrangement, both connections in the housing and additionally oralternatively the filter pot can be shut off relative to the environmentand be hermetically sealed to prevent undesired fluid leakage, becausethe filter device according to the present invention is universallyadjustable. With the closing arrangement of the present invention, aplate valve is realized which closes with extremely operationallyreliability and with a seal and works accessible in any possibleoperational state.

In the normal cycle, the closed filter pot can be sent back to themanufacturer with the polluted filter element as it is removed. Themanufacturer then undertakes suitable waste disposable and reusesreusable parts, for instance, the filter pot. Following suitablecleaning, the reusable parts can be used for new devices or asreplacement parts.

In one preferred embodiment of the filter device according to thepresent invention, the closing arrangement has a nonreturn valveinserted in the drain. The valve opens during the filtering process andis closed upon removal of the filter pot. For this purpose, and in thecase of a possible reverse flow of fluid out of the drain in thedirection of the filter element, a hermetic seal is guaranteed.

In another preferred embodiment of the filter device according to thepresent invention, the closing arrangement has two reinforcement partswith openings arranged one behind the other in the direction of flow ofthe fluid. Each reinforcement part incorporates a separate closing part.Each closing part is held by means of the other closing part, counter tothe force of a power storage device, in its particular setting forfreeing the openings in the reinforcement parts. Upon removal of thefilter pot, one closing part closes off the connection serving thehousing drain. The other closing part closes the inside of the filterelement from its surrounding environment with a seal. A constraintcoupling is advantageously provided between two closing parts, by whichsynchronous opening and closing of the housing connection and of theconnection with the element holder is made possible. Since the openingsof the reinforcement parts are arranged one after the other in the fluidflow direction, any flow resistance effecting the fluid is avoided.

One especially preferred embodiment of the filter device of the presentinvention provides a form-locking connection between the filter elementholder and parts of the housing by means of a torsion-securityarrangement. In an exchange process of the filter pot with the filterelement, the element holder is thrust axially only in the same directionas the twisting or screwing. With no time loss on the part of theoperator, the closing plates with their openings assume precise andproper adjustment of their structural position, arranged offset from oneanother, in order to finally undertake reliable operation from theiroffset structural position.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexes drawings, discloses preferredembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a side elevational view in section of a filter deviceaccording to a first embodiment of the present invention;

FIG. 2 is a top plan view of a closing arrangement in the direction ofarrow II of FIG. 1;

FIG. 3 is a top plan view of a closing arrangement in the form of aplate valve;

FIG. 3a is a side elevational view in section of the plate valve of FIG.3;

FIG. 4 is a top plan view of a torsion-security arrangement for thefilter element;

FIG. 4a is a side elevational view in section of the security-torsionarrangement of FIG. 4;

FIG. 5 is a partial side elevational view in section of the top part ofa filter device according to a second embodiment of the presentinvention;

FIG. 6 is a partial, side elevational view in section of the top part ofa filter device according to a third embodiment of the presentinvention;

FIG. 7 is a top plan view of another embodiment of a plate valveaccording to the present invention;

FIG. 8 is a bottom view of a closing part of a closing arrangement ofFIG. 7;

FIG. 8a is a side elevational view in section of the closing part ofFIG. 8;

FIG. 9 is a side elevational view in section of a reinforcement partprovided for the closing part of FIGS. 8 and 8a; and

FIG. 10 is a top plan view of a closing arrangement comprising theclosing part and the reinforcement part of FIGS. 8, 8a and 9.

DETAILED DESCRIPTION OF THE INVENTION

The filter device according to the present invention has a housing 10with a feed line 12 and a drain 14 for conveying a fluid. Housing 10 canbe connected with a filter pot 16 having a filter element 20 heldsecurely by an element holder 18. Such filter devices are sufficientlyknown that the individual parts of the filter device are described onlyinsofar as their description is needed for understanding the presentinvention.

A closing arrangement, indicated in its entirely in the first embodimentas 22, has two annular sealing flaps 24a and 24b, arranged securitybetween the element holder 18 and the outside periphery and insideperiphery of filter element 20, respectively. A supporting lattice 26 isalso between the filter element inside periphery and element holder 18.Outside sealing flap ring 24a is shown in FIG. 1 in a closed setting.The closing arrangement is opened as soon as a fluid pressure appears infeed line 12. When sealing flap 24a is opened, unfiltered fluid passesthrough the outside periphery of filter element 20, as well as throughthe perforated supporting lattice, into the inside chamber 28 of filterelement 20. Pollutants which may be present remain in filter element 20.The fluid in inside chamber 28 is cleaned.

Interior sealing flap or ring 24b is supported on a tapered sleeve 30 ofa torsion-security arrangement 32. If filter pot 16 is separated fromhousing 10 by unscrewing thread 34, and if fluid feed or flow throughfeed line 12 is terminated, the elastically flexible sealing flaps 24aand 24b, because of their inherent tension or bias, especially if theyare of rubber, are engaged again on the inside periphery of filter pot16 and are in contact with each other in the middle of the filter pot.Consequently, a hermetical seal closes inside chamber 28 of filter pot16, which is at least partially filled with contaminated fluid, from thesurrounding environment. The closing procedure of sealing flaps 24a and24b progresses continually. Closing arrangement 22 automatically closesthe possible flow through points. When a new filter element 20 isinserted and filter pot 16 is screwed into housing 10 by means of thread34, inside sealing flap ring 24b is pushed up over tapered sleeve 30 oftorsion-security arrangement 32, and sealing flat ring 24a is opened bythe fluid feed or flow through feed line 12.

In addition, following removal of filter pot 16, closing arrangement 22automatically closes the connections with feed line 12 and a drain 14.For this, closing arrangement 22 has two closing plates 36a and 36b inthe form of two plates or disks which have openings 40a and 40b (FIG.3), respectively, arranged offset from one another in two differentplanes. The plates or disks can be moved back and forth relative to oneanother under the effect of the bias of an annual disk spring element42, during removal of filter pot 16 for closing openings 40a and 40b.Consequently, a sort of plate valve is used, as shown in greater detailin FIGS. 3 and 3a. FIG. 3 shows top plate or disk 36b turned toward theviewer with the two diametrically opposite openings 40a. Plate or disk36b is positioned thereunder in a second plane further away from theviewer and covered by plate or disk 36a. Openings 40b are offset 90degrees from openings 40a. In the middle of the two plates or disks 36aand 36b, a circular cutout 44 receives and surrounds the sleeve-liketorsion-security arrangement 32.

As shown especially in FIGS. 1 and 3a, the upper plate or disk 36a movesalong the guide formed by the inside border of lower plate or disk 36b,and has a boundary on the border side and facing toward cutout 44. Inthe embodiment of FIG. 1, the boundary is formed of a U-shaped angleprofile 48 forming bearing surfaces. As shown in FIG. 1, upper plate ordisk 36a is supported with its top on disk spring 42. Spring 42 isconfigured such that, under no circumstances, does it cover openings40a. Disk spring 42 is supported in housing 10. Under the spring bias,plate or disk 36a has its angle profile 48 pressed against a projectingbracket 52 integral with annular element holder 18, and consequently, isheld in its position.

The other securely arranged plate or disk 36b is offset downward on itsouter end remove from cutout 44 (FIG. 1) and is supported with its freeend at the point of the offset along a ledge 54 within housing 10. Ifthe previously described filter element exchange is carried out again,filter pot 16 is not removed until disk spring 42 presses movable plateor disk 36a against stationary plate or disk 36b, and thus, hermeticallyseals openings 41a and 41b. The fluid pressures in feed line 12 work inthe direction of the force of the bias of disk spring 42, and thus,reinforce a hermetically sealed closing of closing arrangement 22 in theform of the plate valve with its two plates 36a and 36b.

Closing arrangement 22 has a nonreturn valve 56 inserted in the line fordrain 14, which valve opens during the filtering process and closes withremoval of filter pot 16. Nonreturn valve 56 is supported on atriple-arm plate 58, shown in detail in FIG. 2 and is securely connectedwith housing 10. A longitudinal journal 60 is arranged at the connectionpoint of the three arms of tripe-arm plate 58. A valve member 62, whichextends into a point, has a sleeve-like longitudinal extension 64 guideover journal 60. If no fluid pressure arises in inside chamber 28, valvemember 62 is pressed by a closing spring 66 to engage its conicalclosing surface against a valve seat 68. Valve seat 68 is part ofarrangement 32 to prevent torsion.

When fluid pressure in inside chamber 28 increases above a predeterminedthreshold value, nonreturn valve 56 opens and fluid flows through insidechamber 28, through torsion-security arrangement 32 and the threeopening points 70 between the arms of the triple-arm plate 58 into drain14. Closing arrangement 22 closes as soon as the pressure in insidechamber 28 of filter pot 16 drops below the predetermined thresholdvalue. This can occur, among other times, during removal of filter pot16 and consequently during closing of plate valve 36a and 36b.Furthermore, nonreturn valve 56 closes when the interior pressure indrain 14, for example because of unpredicted pressure points in thehydraulic circuit, becomes greater than the pressure produced by thefluid pressure in feed line 12 in inside chamber 28. Consequently,pressure peaks can be picked up to conserve or protect the filterelement 20.

As shown in FIG. 1, an O-ring 72 is located in a groove within bracket52 facing the torsion-security arrangement 32. O-ring 72 is in contactwith parts of housing 10, and consequently closes off and seals feedline 12 from the inside chamber 28 of filter pot 16. If O-ring 72 isdefective or is not set precisely in position, disturbances arise in thefilter device, which disturbances negatively influence the filteringcapacity. The origin of these disturbances is difficult for the repairexpert to find. To force O-ring 72 as nearly as possible and asuniformly as possible into its predetermined setting, element holder 18for the intended filter element 20 comes into use as a form-lockingconnection with parts of housing 10 through arrangement 32 to preventtorsion.

For this purpose, the form-locking connection has one or two cutoutsarranged opposite one another on element holder 18, in which engage thetwo shoulders 74 associated with torsion-security arrangement 32. Asshown especially in FIG. 4a, the one or two shoulders 74 arrangedopposite one another are configured as longitudinal guides. Elementholder 18 is axially guided by shoulders 74 against radial twisting offilter pot 16. This guiding also precludes any tilting, canting oroblique offsetting of filter element 20.

Furthermore, such form-locking connection is required to avoid thrustingplates or disks 36a and 36b against another when the screwing andunscrewing filter pot 16. Thrusting the plates together could lead tooperational breakdown of the filter device. Akey-port-connection-technology is realized with the form-lockingconnection over a groove-journal-assembly. This arrangement guaranteesthat operators of the filter device cannot use filter elements of othermanufacture. Traditionally, filter elements can easily be obtainedcommercially together with the element holder, but without any insideguide arrangement. Such known filter elements, rotated together with thefilter pot during its screwing in and screwing out, would allow theplate valve to become useless.

For simplicity, the following embodiments are to be described onlyinsofar as they differ significantly from the previous descriptions.Nearly identical reference numbers are used for comparable parts. Thedescriptions of the new embodiments likewise correspond to the original.

For hermetic sealing of filter pot 16, in the FIG. 5 embodiment of thefilter device, plate valves are used as described for the firstembodiment of FIG. 1. Plate valve plates 36a and 36b with openings 40aand 40b and disk spring 42 are shown for closing feed line 12 in FIG. 5.In the direction of flow behind this first plate valve a second platevalve is arranged. The second plate valve comprises correspondingidentical plates or disks 76a and 76b with openings 78a and 78b arrangedin two different planes offset from one another. In this case, however,the bottom stationary plate or disk 76b is supported on a spring element80. Spring element 80 is held in angle profile 82 of the second platevalve corresponding to angle profile 48. Plate valves 36a-36b and76a-76b are controlled by filter element 20 and are closed by means ofthe power storage member 42 when filter element 20 is unscrewed withfilter pot 16. This reinforces the pressure of spring element 80 thrustagainst stationary plate or disk 76b. Movable plate or disk 76a, overthe angle profile 82, forms the detents in closed setting.

In further development of the invention and in a kinematic reversal, theother plates or disks of the plate arrangements could also be designedas movable and the formerly movable plates or disks could be designed asstationary. Furthermore, combinations are also possible in which bothplates or disks of a plate valve could be movable relative to oneanother, with the assistance of a suitable power source, preferably inthe form of disk springs.

In the area of drain 14, the sleeve-like torsion-security arrangement32, corresponding to FIGS. 4 and 4a, is used. A third plate valve isinserted on the inside periphery of element holder 18, and has plates ordisks 84a and 84b with corresponding openings 86a and 86b and a diskspring 88. Plate or disk 84b, arranged on the top in FIG. 5, is insertedin the edge of element holder 18, as is disk spring 88. Second plate ordisk 84a with openings 86a is arranged between plate 84b and disk spring88, and is longitudinally movable under the influence of disk spring 88.This second plate or disk 84a has an annularly projecting longitudinalguide 90 at its disposal. Longitudinal guide 90 engages an annularcutout 92 in the outer plate or disk 84b. Projecting longitudinal guide90 is braced on the bottom of sleeve-like torsion-security arrangement32 and is consequently held at some distance from the first plate ordisk 84b.

With removal of filter pot 16, the third plate valve is automaticallyclosed under the influence of disk spring 88. Bottom valve plate or disk84a is moved against top plate or disk 84b, whereby the second and thirdplate valves are closed and removed with filter pot 16. The first closedplate valve remains in housing 10. In this embodiment, the middle partof the plate valve is closed, and consequently, has no openingcomparable to cutout 44.

Nonreturn valve 56 of FIG. 1 is not present in this second embodimentshown in FIG. 5. However, if pressure peaks in drain 14 should makenecessary the use of a nonreturn valve, such a valve can be incorporatedinside torsion-security arrangement 32.

Another or third embodiment of the filter device is shown in FIGS. 6-10.For closing inlet 12, a plate valve is provided with two closing plates100a and 100b. Closing plate 100b, shown in FIG. 6 at the bottom, isstationary and is supported along its outside periphery on ledge 54 inhousing 10. Top closing plate 100b is movably supported under the biasof a disk spring 104 against bottom closing plate 100b.

The precise construction of this plate valve is illustrated in the topplan view of FIG. 7. Top closing plate 100a is configuredbutterfly-like, with its two wings defining the two openings 102a lyingin the same plane with this plate. The openings are limited at thebottom by the circular plate or disk 100b and are enclosed at the frontby housing parts 10. Plate or disk 100b has flange-like tabs 116projecting radially outward and distributed around its outside peripheryfor support of bottom closing plate 100b on ledge 54 in housing 10. Thetwo wings of top closing plate 100a completely cover the twodiametrically opposite openings 102b of bottom closing plate 100b.

Closing plate 100a has individual downward-projecting flanges 118 on itsbottom to form a longitudinal guide for the closing plate. Flanges 118engage or are received in openings 102b associated with them in eachstage of the procedure incorporating plate 100a, and are propped on orengage the inside edges of the respective cutout 102b. Along its insideperiphery, top plate 100a is guided over a guide ring 120 with radiallyinwardly projecting guide lugs 122 extending along a cylindrical guidesurface 124. Guide surface 124 is part of a housing insert 126 screwedinto drain 14. This insert, for simplicity, is shown in FIG. 7 only, byits outside edge, and can also be configured identical to thetorsion-security arrangement 32 shown in FIGS. 4 and 4a. Upon removal ofelement holder 18 and filter element 20, top closing plate 100a is movedunder the effect of the valve spring 104 into a closed position, closingoff openings 102b. Openings 102a are closed synchronously by bottomclosing plate 100b. When the plate valve is open, the fluid found insidefilter pot 16 flows through feed line 12, top opening 102a and thediametrically opposite opening 102b.

Drain 14 in the filter embodiment shown in FIG. 6 is closed by a closingarrangement 22. This closing arrangement has two opposite, inverselyarranged, but identically configured, reinforcement parts 106a and 106bwith openings 108a and 108b. The openings are arranged one behind theother in the direction of flow of the fluid from the inside chamber 28of filter element 20 to drain 14. Each reinforcement part 106a and 106bis associated with a closing part 110a and 110b, respectively. Eachclosing part is held by means of the other closing part, counter to theforce of a power source 112a and 112b, in its position freeing openings108a and 108b (FIG. 6). Upon removal of filter pot 16, one closing part110a closes off the connection serving as drain 14, and the otherclosing part 110b closes off the inside chamber 28 of filter element 20from the surrounding environment forming a fluid seal. The closedsetting of closing parts 110a and 110b is shown in broken lines in FIG.6.

As shown especially in FIG. 9, each reinforcement part 106a or b isconfigured to be hood-like and surrounds openings 108a or 108b by meansof downwardly bent flanges 128a or 128b. The reinforcement part 106a orb has a bracket-like annular surface 130a or b, supported with its freeoutside edge on an inwardly projecting flange of the housing insert 126,as shown in FIG. 6. Annular surface 130a or b is connected throughflange 128a or b with hood 132a or b of the assembly, which on itsinside, facing annular surface 130a or b, has a cylindrical guidejournal 134a or b. On the side of that assembly hood 132a or b, facingaway from guide journal 134a or b, is a handle 136a or b. The shape ofhandle 136a or b is obtained by spray molding, insofar as a plasticmaterial is used in spray molding the reinforcement part 106a or b.

Reinforcement part 106a or b movably holds a screen-like closing part110a or b, illustrated in greater detail in FIGS. 8 and 8a. As shownparticularly in FIG. 8a, the closing part is spray-injected, preferablyof a plastic material, is configured to be screen-like, and has ajournal-like extension 114a or b inserted in reinforcement part 106a orb. The journal-like extension projects out from the reinforcement part.The screen 138a or b is supported on four supporting flanges 140a or barranged radially relative to journal-like extension 114a or b.Extension 114a or b has a cylindrical cutout 142a or b on its top. Theguide journal 134a or b of the reinforcement part 106a or b can beengaged in cutout 142a or b. Between guide journal 134a or b andcylindrical cutout 142a or b a pressure spring (not shown) is inserted.The pressure spring has a great range of movement, and when compressedrequires a particularly small structural space. The plan view shown inFIG. 10, showing the open state of the distributor arrangement,illustrates reinforcement part 106a or b surrounding closing part 110aor b with opening of openings 108a or 108b, and serving as a guide forclosing part 110a or b.

When filter pot 16 is unscrewed from housing 10, the engagement of theextensions 114a and 114b of closing parts 110a and 110b is retained.Consequently, each screen 138a and b is moved continuously andprogressively into its position shown in FIG. 6 in broken lines, beforethe two extensions 114a and 114b are released from engagement with oneanother. If closing parts 110a and b are in their closed position, thebottom borders of screens 138a and b lie on the inwardly inclined edgesof annular surfaces 130a and b of support parts 106a and b. Openings108a and 108b are hermetically sealed in this closed position. Followingexchange of filter element 20, if filter pot 16 is brought back into itsconnected arrangement in housing 10 as in the representation shown inFIG. 6, this controlled process occurs in the opposite manner.Extensions 114a and 114b of closing parts 110a and 110b execute the opensetting of the hood valve arranged in the middle and working in bothdirections.

The filter device according to the invention can have a reversing valveor a bypass valve unit, as conventionally used with these devices, andthus, are not described in detail. Electronically operated connectionparts could be used instead of the closing and sealing plug 94. Plug 94,among other results, give over the pressure- and pollution-ratios in thefeed line 12, as well as in the drain 14.

While various embodiments have been chosen to illustrate the invention,it will be understood by those skilled in the art that various changesand modifications can be made therein without departing from the scopeof the invention as defined in the appended claims.

We claim:
 1. A filter device, comprising:a housing having first andsecond fluid connections; a filter pot having an open end releasablycoupled to said housing, having a filter element with an inside chamberand having a filter element holder secured to said filter element; and aclosing arrangement including closing means, connected to at least oneof said housing and said filter pot, for preventing undesired fluidleakage during assembly and disassembly of the filter device, saidclosing means having relatively movable first and second closing platespartially defining and limiting first and second openings in saidclosing plates, respectively, said first and second closing plates beinglocated directly adjacent each other in two different, substantiallyparallel planes, said first and second openings being relatively offsetin said two different parallel planes, biasing means coupled to saidclosing plates for relatively moving said closing plates in a lineardirection perpendicular to said two different parallel planes to closecontinuously and progressively said openings to seal at least one ofsaid first fluid connection, said second fluid connection and said openend of said filter pot upon increasing separation of said filter potfrom said housing.
 2. A filter device according to claim 1 whereinsaidfirst closing plate is stationary relative to one of said housing andsaid filter pot; and said second closing plate is movable and responsiveto forces of said biasing means.
 3. A filter device according to claim 1whereinsaid closing plates comprise guide means on borders thereof forguiding relative movement therebetween.
 4. A filter device according toclaim 1 whereinsaid first connection is a drain; and said closingarrangement further comprises a nonreturn valve coupled to said drain,said nonreturn valve opening during filter operation and automaticallyclosing upon removal of said filter pot from said housing.
 5. A filterdevice according to claim 4 whereinsaid nonreturn valve is mounted on asupport plate having a plurality of radially extending arms, said armsengaging said housing and defining fluid flow passageways therebetween.6. A filter device according to claim 1 wheresaid first connection is adrain; said closing arrangement further comprises first and secondreinforcement parts with first and second openings therein,respectively, said first and second reinforced parts being arranged inseries in a fluid flow direction through said housing; first and secondclosing parts are coupled to said first and second reinforcement parts,respectively, for relative movement between open and closed positions;in said open positions of said closing parts, said first and secondopenings in said reinforcement parts are open to allow fluid flowtherethrough; in said closed position of said first closing part, saidfirst closing part closes and seals said first connection; in saidclosed position of said second closing part, said second closing partcloses and seats said inside chamber of said filter element; and biasingmeans, coupled to said closing parts, forces said closing parts to saidclosed positions upon removal of said filter pot from said housing.
 7. Afilter device according to claim 6 whereinsaid first and secondreinforcement parts are dome-shaped and surround said first and secondclosing parts, respectively; and each of said closing parts comprises ajournal extension projecting beyond the respective reinforcement part,said extensions extending toward and engaging each other to move saidclosing parts against said biasing means into said open positions fromsaid closed positions thereof.
 8. A filter device according to claim 1whereinsaid closing arrangement further comprises at least oneelastically, flexible seal means extending between said filter elementholder and said filter pot.
 9. A filter device according to claim 8whereinsaid seal means comprise sealing flaps.
 10. A filter deviceaccording to claim 1 whereinsaid filter element holder is coupled tosaid housing by a form-locking connection over a torsion-securityarrangement.
 11. A filter device according to claim 10 whereinsaidform-locking connection comprises a mating projection and cutout in saidfilter element holder and said torsion-security arrangement.